Walter Roberson

Last seen: Today | Active since 2011

I do not do free private consulting. If you want to bring my attention to something, send a link to the MATLAB Answers location. I am currently caught up to T0099119; if you are waiting on a reply from me for an older issue, please send me a reminder.

Programming Languages:
C, MATLAB, Shell, Perl, Fortran
Spoken Languages:
English

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Answered
Calculate the area of geometry
The first thing you need to do is decide how the user is going to represent the specific shape for calculation purposes. are y...

2 hours ago | 0

Answered
How to distribute random points outwards from a center location?
cx = 3; cy = 5; %as appropriate R = 20; N = 1000; theta = rand(1, N) * (2 * pi); rbase = rand(1,N) * R; [X, Y] = pol2cart...

2 hours ago | 0

Answered
Problem using variable='z^-1' in Z transform with Z^-1 format
Setting the Variable property afterwards just changes the Variable property, without reinterpretting the matrices. It is not a c...

3 hours ago | 0

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MAJOR 25+ YEAR OLD MATLAB BUG. PLEASE, PLEASE FIX! Ctrl-C doesn't work, no way to stop a process.
| appreciate that there are issues with OS implementations, eg memory management, that make this a challenge. That said, I'm qu...

3 hours ago | 0

Answered
got new laptop; can't access matlab from it
https://www.mathworks.com/downloads/ for downloads. You will probably need to deactivate against the old system to activate on ...

9 hours ago | 0

Answered
Has anyone got aaS Matlab toolbox I need it soon kindly help I will be very grateful to you
The current student software downloads are linked from https://www.ansys.com/academic/students Ansys aaS appears, however, to ...

9 hours ago | 0

Answered
find 1s in the Matrix
firstcol = 48; lastcol = 65; offsetcol = 14; idx = firstcol:lastcol; offsetidx = idx-offsetcol; result = YourMatrix(:,offse...

9 hours ago | 0

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Answered
Drawing a boundary box around an image?
My goal is to create a bounding box around the non-zero pixel value region of my image. filename = 'https://www.mathworks.com...

10 hours ago | 0

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Answered
Poisson distribution and discrete distribution
fitdist allows you to fit a distribution to data. I want to fit Y to a Discrete distribution There are an infinite number of d...

10 hours ago | 0

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creating a function nonpivotcols that takes a m*n matrix as input and produces a matrix consisting of the nonpivot columns of the input
[R pcols]=rref(A); A(:,pcols)=[]; You deleted the pivot columns out of A. Whatever is left must be non-pivot columns. [r,fcol...

10 hours ago | 0

Answered
Why does sqlread() not work?
sqllite() is not a Mathworks function. sqlread() is a method that applies to some objects created by the database() command. h...

11 hours ago | 0

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What does it mean to "% extract t and h(t) for time range 5.0<=t<=12.0" when "h=4.0+6.0*t*10^-0.5-(4*10^-0.25)*cos(0.75*pi*t)"?; when
One way: Loop over the indices of the vector of t. At each point, make the "current" t equal to the t vector indexed at the cur...

12 hours ago | 0

Answered
Select multiple radiobutton at the same time
hf=exemple; You run the code in exemple and it returns. You are no longer running any code inside exemple but it set up sev...

21 hours ago | 0

Answered
Cannot execute Figure(3).
q=[0.000000025;0.000000034;0.000000042]; %Calculate manually on 0.75Q, Q, 1.25Q; f=1-exp(-(((k*pi*d)/q))*z); The / opera...

21 hours ago | 0

Answered
Unrecognized function or variable 'Fid2'.
l = fgetl(FID); if strcmp(l(1),'**') fgetl returns a character vector (except at end of file) l(1) will be a sing...

24 hours ago | 1

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Answered
Simulink files compatibility with MATLAB versions
Yes. The Function Block (not the same as MATLAB Function Block) no longer exists. You might want to hold on to one of your previ...

1 day ago | 0

Answered
GPU coder :basic Code Generation failed
I think Cuda Toolkit 11.6 is not supported in your release. I am having difficulty finding the toolkit version that is supported...

1 day ago | 0

Answered
which part of my logic is wrong?
You used the / operator. The / operator is matrix division. P/Q is approximately P*pinv(Q) . In situations such as yours with ro...

1 day ago | 1

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Answered
trisurf: Removing Unwanted Lines and Surfaces from Irregular 3D Plot
You should not do this at the trisurf() level; you should be creating a modifed triangulation https://www.mathworks.com/help/ma...

1 day ago | 0

Answered
3D plot in Simulink
XY Graphs are specifically documented to open a different window for each block, and only permit scalar X and scalar Y. But you ...

1 day ago | 0

Answered
Calculating Hessian without using symbolic functions
No, not unless you can calculate it by hand ahead of time using some other set of external tools. You can estimate the Hessian....

1 day ago | 0

Answered
out of memory error
Pre-allocate out to the final size. This will reduce temporary memory use. Also, using : is more memory efficient than indexing ...

1 day ago | 0

Answered
How do I prevent MATLAB from converting characters into their ASCII equivalent?
zeros() creates a numeric array, with a default data type of double() Any time you assign a char() into a numeric array, MATLAB...

1 day ago | 0

Answered
Incorrectly getting a blank video when using videowriter function to display data
You are not changing the display between getframe() so all of the frames would be the same. If you have pre-computed frames sto...

1 day ago | 0

Answered
Linear constraints using lsqnonlin
lsqnonlin() does not support constraints other than upper bound and lower bound. I suggest you minimize the norm() of F(x,y,z)-...

1 day ago | 0

Answered
i couldn't understand the problem in it
dy = zeros(12,1); You initialize 12 return values but you then only store up to dy(9). You only need zeros(9,1)

2 days ago | 0

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Answered
minibatchqueue or arrayDatastore drops my data precision from double to single
Gpu training does not support double precision. If you look at the available options, precision cannot be selected.

2 days ago | 0

Answered
How do I plot a summation equation?
You are summing exp() of values that are purely imaginary and are mostly not integer multiples of π. The individual entries are ...

2 days ago | 0

Answered
How to change the matlab maximum name length?
No there is no way to do that. The variable names and field names of struct and property names of objects are all stored as fixe...

2 days ago | 0

Answered
dividing defined variable by named variable
a=sqrt((d.^2)*(3^2)) 3^2 is 9 so inside the sqrt() you have 9*d^2. sqrt() of that is sqrt(9)*sqrt(d^2). For positive d that...

2 days ago | 0